The Electroluminescent Application of V-shaped Tröger's Base Compounds

We report the design and evaluation of three V-shaped Tröger's base (TB) derivatives-TB-PhCz, TB-CzPh, and TB-oPhCz-featuring phenylcarbazole moieties as potential host materials for red and green phosphorescent OLEDs. The TB-hosts exhibited high decomposition temperatures (353 °C-399 °C) and glass transition temperatures (∼197 °C), demonstrating excellent thermal stability-an essential attribute for vacuum deposition processes and long-term device reliability. Two device architectures, single-host and co-host systems, were investigated to assess their influence on device performance. The co-host approach, using blends with high-triplet-energy electron transport materials (CN-T2T or B3PyMPM), significantly enhanced charge transport, exciton confinement, and operational stability. Notably, the red-emitting co-host device B1 (TB-PhCz:CN-T2T) achieved a 50% increase in external quantum efficiency (EQE) over its single-host counterpart. While green devices based on TB-CzPh and TB-oPhCz exhibited higher peak efficiencies in single-host configurations, co-host devices B2 and B3 demonstrated superior luminance stability and reduced efficiency roll-off. These outcomes highlight the critical role of molecular structure in charge mobility and exciton dynamics. Among them, device B2 achieved the highest luminance (58,784 cd/m²) with no observable roll-off at 100 cd/m², confirming the excellent charge balance enabled by TB-CzPh.